Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Posting-Version: version B 2.10 5/3/83; site umcp-cs.UUCP
Path: utzoo!linus!philabs!seismo!rlgvax!cvl!umcp-cs!james
From: james@umcp-cs.UUCP
Newsgroups: net.physics
Subject: Speeds of light
Message-ID: <2399@umcp-cs.UUCP>
Date: Sun, 4-Sep-83 01:15:42 EDT
Article-I.D.: umcp-cs.2399
Posted: Sun Sep  4 01:15:42 1983
Date-Received: Mon, 5-Sep-83 04:23:30 EDT
Organization: Univ. of Maryland, Computer Science Dept.
Lines: 25

Below, M-M stands for Michelson-Morley.

Please allow me to clarify my statement in net.physics.  First of all,
I was using the terms north-bound and south-bound only because I felt
that they might more simply convey the idea of opposite directions
to a general audience.  Second, I was not referring to the M-M
experiment as it deals with aether.  What I was stating is the
possibility that the speed of light (in a vacuum) is not a constant
for all directions.  Because of the difficulty with the synchronization
of two clocks separated by a distance, it is possible only to measure
the time it takes for a light ray to travel in some loop.  Therefore,
the speed of light could be different in the positive-X-direction and the
negative-X-direction, as long as the average were the currently observed
single 'speed of light'.  What the M-M experiment tells us is that
the measured average speed of light in the X directions and the Y
directions are the same.

It may be possible to measure the speed of light in a SINGLE direction
by arranging to have the light ray travel in a circular orbit about
a large black hole (source of gravity sufficient to bend the ray),
or by having the ray travel in a 'great circle' in space (which could
possibly exist if space has the topology of a torus or some other
topology permitting similar tricks).

  --Jim O'Toole